Explosives are categorized as primary or secondary based on their susceptibility to initiation. Primary explosives are highly susceptible to initiation and are used in small quantities to ignite secondary explosives, main charges, propellants, or fuel. Requirements for primary explosives include sufficient sensitivity to be detonated reliably while not being exceedingly dangerous to handle as well as sufficient thermal stability to not decompose on extended storage or thermal insult.
Two common primary explosives are lead azide and lead styphnate, but both emit toxic lead upon detonation. Because of this toxic residue, the development of a lead-free primary explosive is needed.